1. Technical Field
The present invention relates to a device and a method for determining a walking condition of a walker having a plurality of legs.
2. Description of Related Art
When a device for aiding a person with deteriorated muscle strength in walking is used, it is necessary to accurately determine a walking condition, that is, whether the person is walking on a level ground, walking up or down stairs, etc. in order to properly aid the walking by the device. For this purpose, Japanese Laid-Open Patent No. 7-163607, for example, has proposed a method for determining a walking condition on the basis of pressures applied to soles of a walker measured by pressure sensors. Furthermore, Japanese Laid-Open Patent No. 2000-325329, for example, has proposed a method for determining a walking condition on the basis of angles of legs of a walker.
However, according to the determining method based on the pressures applied to soles, portions of the soles where the pressure sensors are provided may not touch stair steps especially when a walker is going up or down stairs, and walking conditions may be erroneously determined. For instance, there are cases where the walker lands on a stair at his or her tiptoes, whereas the pressure sensors are provided at their heels. Furthermore, distribution of pressures applied to soles varies, depending upon the shapes of soles of footwear, so that walking conditions may also be erroneously determined. If footwear having pressures sensors provided in its soles is used, then the pressure sensors and an arithmetic processing unit or the like for determining walking conditions must be connected or disconnected through communication lines or electric wires each time the footwear is attached or detached. This may cause the walker to feel bothersome.
According to the determining method based on the angles of legs, walking conditions may not be accurately determined, depending on lengths of the legs of a walker. For instance, when walkers climb the same stairs, the extent to which their thighs are raised for walking differs according to the length of their legs. As a result, it may be erroneously determined that a walker is climbing stairs if the walker is short, while it may be erroneously determined that the walker is walking on a level ground if the walker is tall.
Especially in the walk aiding device, erroneous determination of walking conditions leads to excessive or inadequate aiding power imparted to a walker, adversely affecting the walking.
Accordingly, the present invention has been made with a view toward solving the problems described above by providing a device and a method that allow walking conditions to be determined easily and accurately, regardless of differences in landing spots on soles or in length of legs of walkers.